Melting furnace and method of constructing and operating same



Oct. 24, 1933.

A. W'. SCHEIDT MELTING FURNACE AND METHOD OF CONSTRUCTING AND OPERATING SAME Filed March '7, 1936 llllllllll'l Patented @ct. 24, 1933 UNITED STATES PATENT OFFICE Alfred VI. Scheidt, Sewaren, N. 3., assigncr to The Electric Smelting a Aluminum Company, Cleveland, Ulric, a. corporation of Ohio Application March l, 193%. Serial No. 434,129

' Claims.

This invention relates to melting furnaces, and particula'ly to the construction of the furnace bottom, and to the method of operating the furnace.

The object of the invention is to provide a durable furnace bottom which will resist the action of corrosive materials and thus obviate the nccessity of frequent shutting down for repairs, and which will not contaminate such mateiials with impurities, and a method of operation to produce such results.

The invention consists of a furnace bottom made of cast iron or cast steel plates, suitably supported from below so as to provide for air cooling, and a superposed lining of refractory material with an always-open bottom tap hole from which the molten material is withdrawn, the refractory lining as it wears or is eaten down being replaced by accumulation of the material being melted. thus protecting the metal plates from the burning effect of the hot furnace gases; and the invention further consists of the method of operating such a furnace, as I will proceed now more fully to explain and finally claim.

In the accompanyin drawing illustrating the invention, in the several figures of which like parts are similarly designated, Figure l is a longitudinal sectional elevation of suflicient of the furnace to serve the purposes of this case. Fig. 2 is a horizontal section on line 2-2 of Fig. l, and Fig. 3 is a cross-section on line 3-3 of Fig. "1. I In the manufacture of the product of the pat ent of Alfred H. Cowles, No. 1,745,844, dated Febmarry a, 193i sodium-silico-aluminate, sodium- :neta-sllicate, and other similar substances comprising, in the first case, the mixing in suitable proportions of silica, alumina and alkali metal carbonate, and in the second case of silica sand and alkali metal carbonate, and then heating to fusion, the reaction takes place to completion, and the desired product can be drawn off at once. It has also been found that when such charges are melted and retained, even for a short time, in a furnace, in the form of molten liquid, such liquid usually form the bottom and sides of such furnace, and it is necessary to shut down such furnace for repairs at frequent intervals.

The furnace usually employed in such manufacture, is of the reverberatory type and is commonly regenerative. The charge is added to the furnace through holes in the roof or arch of the furnace and the material after melting is tapped through a hole or slot in the lower end of the furnace, which hole or slot is plugged with brick is extremely corrosive to the materials which and the clay or similar stopper while the charge is melting. The furnace is not tapped until substantially all of the charge is melted, and so for all the time during which the charge is melting the side blocks and part of the hearth are in con tact with the extremely corrosive molten material, which accordingly eats through the blocks in a short time, and requires repairs. Further, when the charge is tapped a large quantity of molten material must be handled at once.

The furnace of my invention is here shown in part as a reverberatory furnace 1, with a front bay 2, inopen communication through mouth 3 with the reverberatory furnace. In this bay the bottom is made of cast iron or cast steel plates 4, or at least that portion of the bottom which is principally exposed to the corrosive action of such molten materials, the area around and behind the tap hole 5. On plates I place a refractory lining 6. which m y be of any good quality of dense fire brick. The plates are supported above the floor or ground level by beams 7.

The corrosive hot liquid material flowing over such plates and 1 ing soon largely eats away such lining, and l places it with an accumulation of material chilled in place by the relatively cooler iron or steel, or else by accumulation of molten material or both. In any case the result is to protect the plates from the oxidizing and burning effect of the hot furnace gases on exposed hot iron or steel.

The purpose of placing the refractory lining on such metal bottom, is to protect the metal plates from the oxidizing or burning effect of hot gases during the time when the furnace is being heated up.

The metal plates may be cooled by contact with the atmosphere on their lower sides, by blowing air against them, or they may be designed to be cooled by water'as required in special cases. I have found even the first method satisfactory when the plates are properly designed'with stiffening and radiating fins as indicated at 8, Fig. 3, to resist warping and to facilitate cooling of the plates.

In charging my furnace, I charge a large quantity of material through holes in the roof or arch whereupon the material falls and builds up in conical piles. I then distribute the charge in the furnace by means of long iron hoes or pushers through working doors in the back of the furnace, in such a manner that the side walls and bottom are covered. I then make wide grooves in the charged material, so that when the material melts r the surface of the batch the molten liquid formed flows naturally and easily to the tap hole 5, which I place in the lowest part of the furnace, and maintain open throughout. When the batch is melted down so that there is room in the furnace to accommodate a new batch but before any considerable portion of the bottom is uncovered, I add a new batch and distribute as before. By operating in this way, I keep the corrosive hot liquid material formed in contact with the unfused material of the batch, and thus protect the walls and bottom of my furnace and prevent contamination from the material dissolving such walls and bottom.

In my concurrent application for patent for melting furnaces with secondary heating fea-,

tures, Serial No. 434,130, filed March ,1, 1930, I have duplicated the structural features here explained and have added to them the secondary burner which may be and preferably is employed here.

Variations in the details of construction are permissible within the principle of the invention and the claims following.

What I claim is:

1. The combination of a melting furnace, a chamber in communication with said melting furnace to receive fused material from said furnace and having a bottom comprising a metal plate having a lining, at least a portion of said lining consisting of chilled material fused in the melting furnace, said metal plate being initially lined with a refractory material to protect the plate from the corrosive effect of the hot furnace gases while the material in the melting furnace is being heated, and means for cooling said plate so that when fused material flows into the chamber and decomposes the refractory material, a portion of the fused material flowing into the chamber will be chilled, thereby providing a permanent lining for the metal plate.

2. The combination of a melting furnace for preparing soluble detergent material composed of an alkali metal silicate or an alkali aluminasilicate, a chamber in communication with said melting furnace to receive the detergent in a fused state from said furnace and having a bottom comprising a metal plate having a lining, at least a portion of said lining consisting of chilled material fused in the melting furnace, said metal plate being initially lined with a refractory material to protect the plate from the corrosive effect of the hot furnace gases while the detergent in the melting furnace is being heated, and means for cooling said plate so that when fused detergent flows into the chamber and decomposes the refractory material, a portion of the detergent flowing into the chamber will be chilled, thereby providing a permanent lining for the metal plate.

3. The process of preparing fused material in a melting furnace having a chamber provided with a bottom metal plate in communication therewith, which comprises charging material in the melting furnace, supplying hot furnace gases to fuse at least the upper portion of the material, protecting the upper surface of the metal plate from the corrosive effect of said gases by means of refractory material, causing the fused material to flow from the upper surface of the charge into the communicating chamber and cooling the lower surface of the metal plate so that as the fused material decomposes the refractory material, a portion of the fused material will be chilled and will protect the metal plate from the corrosive effect of the hot furnace gases.

4. The process of preparing a soluble detergent material in a melting furnace having a chamber provided with a metal bottom plate in communication therewith, which comprises charging material in the melting furnace, supplying hot furnace gases to fuse at least the upper portion of the soluble detergent, protecting the upper surface of the metal plate from the corrosive effect of the furnace gases by means of refractory material, causing the fused detergent to flow from the upper surface of the charge into the communicating chamber and cooling the lower surface of the metal plate so that as the fused detergent decomposes therefractory material, a portion of the fused detergent will be chilled and will protect the plate from the corrosive effect of the hot furnace gases.

5. The process of preparing an alkali metal silico-aluminate in a melting furnace having a chamber provided with a metal bottom plate in communication therewith, which comprises charging material in the melting furnace, supplying hot furnace gases to fuse at least the upper portion of the alkali metal silico-aluminate, protecting the upper surface of the metal plate from the corrosive effect of the hot furnace gases by means of refractory material, causing the fused alkali metal silico-aluminate to flow from the upper surface of the charge into the communicating chamber and cooling the lower surface of the metal plate so that as the fused alkali metal silico-aluminate decomposes the refractory material, a portion of the fused alkali metal silicoalumi nate will be chilled and will protect the metal plate from the corrosive action of the hot furnace gases.

ALFRED W. SCHEIDT. 

